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  • Undergraduate Poster Abstracts
  • Other Agricultural Sciences

    FRI-206 THE SCREENING OF BACTERIOCIN ACTIVITY WITHIN PSEUDOMONAS SYRINGAE SENSU LATO TO DETERMINE IF THERE IS A CORRELATION BETWEEN PHYLOGENETIC RELATEDNESS AND KILLING ACTIVITY

    • Julio Martinez ;
    • Kevin Hockett ;
    • Carolee Bull ;

    FRI-206

    THE SCREENING OF BACTERIOCIN ACTIVITY WITHIN PSEUDOMONAS SYRINGAE SENSU LATO TO DETERMINE IF THERE IS A CORRELATION BETWEEN PHYLOGENETIC RELATEDNESS AND KILLING ACTIVITY

    Julio Martinez1, Kevin Hockett2, Carolee Bull3.

    1University of California, Monterey Bay, Seaside, CA, 2The University of Arizona, Tucson, AZ, 3Agricultural Research Service, U. S. Department of Agriculture, Salinas, CA.

    Bacterial plant pathogens present challenges to agricultural food production worldwide. Current methods to control these pathogens are inefficient and cause negative environmental impacts; therefore, it is important to find other methods to advance the control of these pathogens. Bacteriocins, which are protein-based toxins produced by bacteria that are inhibitory towards other bacteria, present opportunities to develop efficient pathogen control strategies. The spectrum inhibition activity of a given bacteriocin is specific; thus, it is necessary to determine if there are general trends that influence targeting activity across many related strains. Previous research has shown that bacteriocins tend to target strains within the same species as the producer, compared to strains belonging to different species. We were interested to see if this trend extended to the subspecies level, i.e., do more closely related strains within a species tend to target each other more so than more distantly related strains within the same species? Pseudomonas syringae (a pathogen responsible for a number of economically important diseases in crops) is an ideal species for this research, as the phylogenetic diversity across this species has been well characterized. We conducted a comprehensive screening of 60 strains of P. syringae to determine if there is a correlation between relatedness and bacteriocin activity. Bacteriocin activity was assessed using standard overlay methods. The results indicated no correlation between relatedness and bacteriocin activity. We tested the alternative hypothesis that bacteriocin activity is correlated with ecology (i.e., plant host) or biogeography. Preliminary analysis supports ecology as an important driver of bacteriocin activity.

    FRI-205 EVALUATING FATTY ACID PROFILES FOR SUBSPECIES CHARACTERIZATION OF XYLELLA FASTIDIOSA

    • Cinthya Tovar ;
    • Christopher Wallis ;

    FRI-205

    EVALUATING FATTY ACID PROFILES FOR SUBSPECIES CHARACTERIZATION OF XYLELLA FASTIDIOSA

    Cinthya Tovar1, Christopher Wallis2.

    1College of the Sequoias, Visalia, CA, 2Agricultural Research Service, U. S. Department of Agriculture, Parlier, CA.

    Numerous strains of Xylella fastidiosa, a Gram-negative bacterium, infect a broad range of host plants, causing diseases such as almond leaf scorch and Pierce’s disease of grapevines. While living inside the host xylem vessels, X. fastidiosa generates biofilms that disrupt the uptake of water and nutrients, which could impact crop production yields. Therefore, additional research is necessary to differentiate and characterize subspecies of X. fastidiosa in order to prevent and control disease outbreaks. One way to better define the X. fastidiosa subspecies is by cell membrane fatty acid analysis, a widely-used phenotypical method for strain identification. The objective of this study is to evaluate fatty acid profiles of 6 different California X. fastidiosa isolates using quantitative fatty acid esterification to determine cell membrane differences. Dendrogram cluster and principal component analysis (PCA) reflect X. fastidiosa hierarchical clustering and subspecies relatedness based on significant fatty acid peaks. We expect 2 separate clusters of X. fastidiosa strains, confirming cell membrane differences in the presence of saturated, branched-chain 16:0 and 17:0 fatty acid peaks. This study formulates a general understanding of X. fastidiosa subspecies characterization, correlating with previous genetic studies, and provides potential characterizing efforts to better regulate and manage disease crop outbreaks.

    THU-205 FIELD OBSERVATIONS OF ASCOSPORE DISCHARGE OF MONILINIA VACCINII-CORYMBOSI IN NORTHERN HIGHBUSH BLUEBERRIES

    • Gina Dabbah ;
    • Annemiek Schilder ;
    • Timothy Miles ;

    THU-205

    FIELD OBSERVATIONS OF ASCOSPORE DISCHARGE OF MONILINIA VACCINII-CORYMBOSI IN NORTHERN HIGHBUSH BLUEBERRIES

    Gina Dabbah1, Annemiek Schilder2, Timothy Miles1.

    1California State University Monterey Bay, Seaside, CA, 2Center for Integrated Plant Systems, Michigan State University, East Lansing, MI.

    Monilinia vaccinii-corymbosi (Mvc) is the causal agent of mummy berry, a potentially devastating fungal disease in North American highbush blueberries (Vaccinium corymbosum L.). M. vaccinii-corymbosi, can account for  more than an 80% reduction in crop yield. To improve disease management practices, we quantified the environmental variables that impacted levels of ascospore discharge. A Burkard spore trap was used to collect ascospores within blueberry fields near Grand Junction and Nunica, Michigan in the springs of 2002, 2003, 2004, and 2009. The spore trap measured airborne ascospores on an hourly and daily basis. Weather data including relative humidity, soil moisture, and air temperature, were also collected from Michigan State University’s Enviroweather network. A previously developed degree-day model from another region was also assessed to compare amount of chill-hours (hours < 7.2 ˚C) needed for wintering and degree-days (days > 7.2 ˚C) acquired. We found ascospore discharge was inversely related to daily relative humidity. The majority of ascospores were discharged after 60 - 80 growing degree-days and after 3,000 chill-hours were attained. Peak ascospore discharge occurred when apothecia cup sizes reached 6 mm. The results from this study may be used to better predict the timing of ascospore discharge in order to optimize fungicide application timing.

    THU-204 ANALYSIS OF THE RIVER CONTINUUM CONCEPT OF FUNCTIONAL FEEDING, GROUP ABUNDANCE, AND RICHNESS FOUND IN THE PREMONTANE TROPICAL STREAMS OF COSTA RICA

    • Jackalyn Kandle ;
    • Justin Montemarano ;

    THU-204

    ANALYSIS OF THE RIVER CONTINUUM CONCEPT OF FUNCTIONAL FEEDING, GROUP ABUNDANCE, AND RICHNESS FOUND IN THE PREMONTANE TROPICAL STREAMS OF COSTA RICA

    Jackalyn Kandle1, Justin Montemarano2.

    1University of Wyoming, Laramie, WY, 2Armstrong State University, Savannah, GA.

    Stream ecosystem function and water quality are widely used in habitat assessment. Therefore, mechanistic drivers of macroinvertebrate community structure and function can help predict how anthropogenic disturbances impact these communities. The River Continuum Concept (RCC) is a conceptual model explaining shifts in macroinvertebrate community structure and function, but it has primarily been developed and tested in forested, temperate streams. We investigated if macroinvertebrate functional feeding groups (FFG) abundance and diversity are predicted by the RCC in forested, premontane, tropical streams found at Las Cruces Biological Station in southwest Costa Rica. Twelve sites were chosen based on the stream order visually on a map and ease of access to trails in the study site. D-Net samples were taken in a riffle and a pool at each of the 12 stream sites varying in stream order. A principle components analysis (PCA) was used to calculate stream order from stream characteristics such as, distance from source, width, depth, slope, and discharge, and FFG abundance and richness were regressed with stream order. Overall abundance and abundance of collectors increased with stream order, but no relationship was detected for abundance or richness of all other FFGs (e.g., shredders, predators, and scrapers). Our results indicate that the RCC, initially developed from temperate systems to predict FFG shifts in abundance and richness, is weakly supported in tropical streams found in Costa Rica.

    FRI-204 EFFECTS OF ENZYME LOADING ON EXTRUSION AND ALKALI EXTRUSION PRETREATED SWEET SORGHUM BAGASSE

    • Matthew Maxwell ;
    • Danielle Bellmer ;

    FRI-204

    EFFECTS OF ENZYME LOADING ON EXTRUSION AND ALKALI EXTRUSION PRETREATED SWEET SORGHUM BAGASSE

    Matthew Maxwell1, Danielle Bellmer2.

    1Southeastern Oklahoma State University, Durant, OK, 2Oklahoma State University, Stillwater, OK.

    Biofuels have the potential to mitigate the demand for fossil fuels, reduce the greenhouse gas effect, and greatly expand the market for renewable energy. Sweet sorghum is a promising bioenergy crop due to its high productivity, low input requirements, and versatility. It has tremendous carbohydrate potential if the available starch, cellulose, and hemicellulose can be converted to fermentable sugar in addition to the existing soluble sugars. Extrusion pretreatment using twin-screw extrusion technology has been used on various feedstocks such as switchgrass, corn stover, etc. In addition, alkali soaking in combination with extrusion has been used to help break down lignin in order to better access the cellulose and hemicellulose in lignocellulosic feedstocks. The objective of this experiment was to evaluate the effects of extrusion and alkali extrusion as a pretreatment method for enzymatic hydrolysis of sweet sorghum. A twin-screw extruder was used to pretreat sorghum at 110 °C with and without alkali pretreatment (4% sodium hydroxide). Samples from each pretreatment were subjected to enzymatic hydrolysis of cellulose and starch at a solid loading of 6%. Samples were loaded with 3 different levels of cellulase and xylanase enzymes. Samples were analyzed for carbohydrates using an HPLC. Sugar yields were compared to enzymatic hydrolysis of non-pretreated sorghum samples. Results show that extrusion pretreatment with and without alkali results in increased carbohydrate conversion to sugars compared to untreated samples. As expected, increased enzyme levels resulted in increased sugar yields.

    THU-206 BEET CURLY TOP VIRUS IN NEW MEXICO CHILE

    • Angie Mestas ;
    • Lisa Willis ;
    • Deana Baucom ;
    • Rebecca Creamer ;

    THU-206

    BEET CURLY TOP VIRUS IN NEW MEXICO CHILE

    Angie Mestas1, Lisa Willis2, Deana Baucom1, Rebecca Creamer1.

    1New Mexico State University, Las Cruces, NM, 2Dine College, Crownpoint, NM.

    Beet curly top virus is damaging to the New Mexico chile production. The disease, characterized by severe stunting and yellowing, can also result in a loss of fruit production if the plant is infected early in the growing season. The virus is transmitted to the plant during feeding by the beet leafhopper, Circulifer tenellus. This insect overwinters on weeds, primarily London rocket, Sisymbrium irio, and kochia, Kochia scoparia. Interestingly, these overwintering hosts are asymptomatic. Research was done to ascertain whether strain and titer of the virus account for this. Chile and weed samples were collected at Leyendecker Plant Science Research Center in Las Cruces, New Mexico. DNA extractions were run through polymerase chain reactions using primers designed to differentiate strains of beet curly top virus. Of the 130 samples analyzed, 25 tested positive for curly top virus. Pepper curly top virus was the most common. All samples that tested positive came from chile plants. No weed samples tested positive for the presence of curly top virus. This is perhaps due to the low amount of virus in these alternate hosts. Future work will be done to quantify virus titer using real-time polymerase chain reactions.